TRAVIS: try to fix make check

.travis.yml

@@ -4,6 +4,7 @@ env:
     global:
         secure: "BB9eiRNXC1PfNRLEifc0yQQZnM25zqaWNGVWN+atzT+NkxhVKyVr8+DoyPYaa8tOKybuSZhVkKnIiCd8iGMe3v+WyuHKFuhdiwdnEQhxbBlUCb9dDLEexI+J8QiYwC8AW/t6H9LWVwSka0RI3GJujJ8HKIBzW45I/j+1NlUte8U="
 before_script:
+    - export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:"/usr/local/lib"
     - sudo apt-get install -qq libgmp-dev libmpfr-dev doxygen graphviz cmake libcunit1 libcunit1-dev
     - sudo apt-get remove doxygen
     - wget http://www.flintlib.org/flint-2.4.3.tar.gz